Make OpenAPIRuntime depend on FoundationEssentials only

[weissi]

Motivation

FoundationEssentials contains only the more modern types and comes in (on non-Darwin) much more lightweight than Foundation which also includes a lot of legacy stuff from swift-corelibs-foundation.

Ideally, the OpenAPIRuntime should be happy with just FoundationEssentials which contains everything that I think it needs (JSON, Date, URL, Data, ...).

Proposed solution

Replace all import Foundations with import FoundationEssentials.

Alternatives considered

No response

Additional information

No response

[czechboy0]

We'll need to import conditionally, as FoundationEssentials isn't available on all platforms.

The mechanism for doing this without breaking API will likely be to add a default trait with the "full Foundation" imports, allowing adopters to turn off default traits and only get the code that requires FoundationEssentials. That'll require Swift 6.1.

[weissi]

We'll need to import conditionally, as FoundationEssentials isn't available on all platforms.

The mechanism for doing this without breaking API will likely be to add a default trait with the "full Foundation" imports, allowing adopters to turn off default traits and only get the code that requires FoundationEssentials. That'll require Swift 6.1.

You should just write

#if canImport(FoundationEssentials)
import FoundationEssentials
#else
import Foundation
#endif

Of course this will only work iff you haven't actually used any legacy Foundation types in your API.

[czechboy0]

Yeah that's the idea, but we can't do it without traits, otherwise it's a breaking change: apple/swift-metrics#158 (comment)

[weissi]

Yeah that's the idea, but we can't do it without traits, otherwise it's a breaking change: apple/swift-metrics#158 (comment)

Whilst it's true that this is observable by others in theory, I don't think it applies to OpenAPIRuntime. It's just not as core of a package as swift-metrics & swift-crypto. Much much fewer people will depend on it and we can audit it by searching github.

Furthermore, OpenAPI also has the transports, both of AHC / URLSession also import Foundation which means the potential for breakage should be very very small.

I really don't think it's worth using traits for this theoretical breakage. I doubt there is any real world code that relies on import Foundation coming from a place that has import OpenAPIRuntime.

[czechboy0]

apple/swift-metrics#158 (comment)

[weissi]

apple/swift-metrics#158 (comment)

OpenAPIRuntime is not SwiftMetrics. Almost everywhere also import OpenAPI{URLSession,AsyncHTTPClient. Tbh in my github search I couldn't find any mention that doesn't either also import a transport or Foundation in the lines around it...

If you really feel you can't do that (which is think is just making your own life hard), the way to solve it is

1. Make a new module OpenAPIRuntimeEssentials and move everything in there
2. Have a single file in OpenAPIRuntime which import Foundation; @_exported import OpenAPIRuntimeEssentials.

That prevents bugs and accidental legacy usage whilst keeping existing behaviours.

[Lukasa]

The above is my proposed plan for swift-asn1 and swift-certificates, incidentally, which I expect to do in the next couple of weeks.